兰州市城区大气细颗粒物中多环芳烃来源解析

Source apportionment of PAHs in fine particulate matter in urban area in Lanzhou

目的探讨兰州市城区大气细颗粒物(PM_(2.5))中多环芳烃(PAHs)的污染水平及来源。方法选择兰州市城关区和西固区作为采样点,采集2015年1月至2016年12月每月10—16日大气PM_(2.5)样品,检测样品中PAHs,并采用特征比值法和主成分分析法判断其主要来源。结果大气PM_(2.5)日平均质量浓度为采暖期高于非采暖期,差异有统计学意义(P<0.01)。除2环外的12种PAHs单体日平均质量浓度均为采暖期高于非采暖期,差异有统计学意义(P<0.05);采暖期PAHs以4环为主,非采暖期以3环为主。采暖期PAHs主要来源于机动车尾气排放和天然气燃烧、煤炭燃烧;非采暖期来源于机动车尾气排放、煤炭燃烧。结论兰州市城区采暖期PAHs污染较非采暖期严重,PAHs主要来源于机动车尾气排放。

Objective To explore the source and level of plycyclic aromatic hydrocarbons（PAHs） in ambient PM2.5 in urban area of Lanzhou. Methods During the period from the 10 th to the 16 th day in each month, PM2.5 samples were regularly collected in Xigu district and Chengguan district from January 2015 to December 2016, PAHs were estimated and source of PAHs were obtained from the factor analysis and principal component analysis（PCA） method. Results The average daily PM2.5 mass concentration in heating period was significantly higher than that in non-heating period（P〈0.01）. Except for 2-ring PAHs,the average daily concentration of 12 PAHs were all significantly higher in heating period than in non-heating period（P〈0.01）;The detected PAHs in heating period were mainly 4-ring PAHs, while in non-heating period were mainly 3-ring PAHs. Two diagnostic method comprehensively revealed that the PAHs in heating period mainly originated from vehicle exhaust emissions and natural gas and coal-fired, in non-heating period, they come from vehicle exhaust and coal-fired emissions. Conclusion The pollution of PAHs in heating period is more serious than in non-heating period, mainly originates from vehicle exhaust emissions.